JCL Day 3
Agenda for Day 3 VSAM data sets Definition & Types Record Structure Commands for VSAM files Generation Data Groups Definition JCL’s for GDG’s Storage Management System Definition & requirements
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VSAM DATASETS (virtual storage access method) • These are the logical datasets for storing records and are known as clusters. • The term cluster is used because there are two components for many VSAM datasets that are : Index component - which contains the index Data component - which contains the actual data
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VSAM DATASETS (Types) KSDS Key Sequenced Data Sets
ESDS Entry Sequenced Data Sets
RRDS Relative Record Data Sets LDS Linear Data Sets
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VSAM DATASETS (KSDS - Key Sequenced Dataset) • These are datasets which are stored in the order of a key field. • The records can be accessed either sequentially or randomly by the record key. • in VSAM as discussed earlier keys are stored separately in an index and the record is accessed in two ways. First the key in the index is located Then on the basis of the information stored in the index for that particular key, the record is located Copyright © 2005, Infosys Technologies Ltd
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VSAM DATASETS (KSDS - Key Sequenced Dataset) • Vsam stores records in the data component in units called control intervals(CI) Unused Space Control Field Record 1
Record 2
Record 3
Free space
CISZ ( CONTROL INTERVAL SIZE) Copyright © 2005, Infosys Technologies Ltd
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(KSDS - Key Sequenced Dataset) //ER5077J JOB CLASS=A,NOTIFY=ER4857 //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DEFINE CLUSTER(NAME(ER5077.VSAM.KSDSFILE) INDEXED VOLUME(INUSR2) RECSZ(80 80) TRACKS(1 1) KEYS(4 0) CISZ(4096)
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FREESPACE(3 3)) DATA
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(NAME(ER5077.VSAM.KSDSFILE.DATA)) INDEX (NAME(ER5077.VSAM.KSDSFILE.INDEX)) /*
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REPRO • REPRO is used to copy VSAM and non VSAM datasets. //ER5077J JOB NOTIFY=&SYSUID //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * REPRO – IDS(ER5077.INPUT.FORVSAM) – ODS(ER5077.VSAM.KSDSFILE) /*
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LISTCAT • LISTCAT gives you the catalog information of the cluster
//ER5077J JOB ,,CLASS=A,NOTIFY=&SYSUID //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * LISTCAT ENTRY(ER5077.VSAM.KSDSFILE) ALL /*
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DELETE • DELETE gives you option to delete the data sets //ER5077J JOB ,,CLASS=A,NOTIFY=&SYSUID //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DELETE ER5077.VSAM.KSDSFILE /*
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Generation Data Groups (GDGs) A Generation Data Group (GDG) is a group of chronologically or functionally related data sets.
Processing of a GDG 1) Adding a new generation 2) Retaining the previous generation 3) Discarding the oldest generation
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Creating Generation Data Group 1) 2) 3)
Create a GDG Base Entry Create a GDG model data set label Create a Generation dataset model
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Create GDG base entry Create an index for the GDG //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DEFINE GDG (NAME(ER5077.PAY.ROLL) LIMIT(3) EMPTY SCRATCH) /*
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Creating a model dataset For Non SMS managed datasets, define a model dataset (DSCB) such that new GDG created will use prespecified parameters DSCB supplies the DCB &EXPDT subparameters for the GDG The model dataset must be cataloged It is linked to the GDG via a “DCB=model name” on creating new GDG’s
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Create DSCB
//ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IEFBR14 //DD1 DD DSN=ER5077.PAYROLL,DISP=(,KEEP), // SPACE=(TRK,(0)),VOL=SER=,UNIT=SYSDA, // DCB=(RECFM=FB,LRECL=80,BLKSIZE=800)
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Create GDS (generation data set) //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IEFBR14 //DD1 DD DSN=ER5077.PAY.ROLL (+1), // DISP=(NEW,CATLG), // SPACE=(TRK,(1,1)), // UNIT=SYSDA, // DCB=ER5077.PAYROLL
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Deleting GDG Catalog Entries •Delete a model //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DELETE ER5077.PAYROLL PURGE /* •Delete an allocated GDG and deletes all GDS’s //ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * DELETE ER5077J.PAY.ROLL PURGE FORCE /* Copyright © 2005, Infosys 17 Technologies Ltd
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Listing of GDG Catalog Information
//ER5077J JOB ,,NOTIFY=&SYSUID,CLASS=A //STEP1 EXEC PGM=IDCAMS //SYSPRINT DD SYSOUT=* //SYSIN DD * LISTCAT GDG ENTRIES(ER5077J.PAY.ROLL)ALL /*
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SMS (Storage Management Subsystem) • SMS is an optional feature of MVS. • It is a tool that is used to improve the management of available disk space. • Data sets created under SMS are known as SMS managed datasets . • PDS are known as PDSE when converted to SMS managed datasets can be done by IEBCOPY. Under SMS while creating a dataset you need to specify : - STORCLAS instead of UNIT - DATACLAS instead of DCB& SPACE - MGMTCLAS for migration of datasets.
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SMS (Storage Management Subsystem) • Generally, your existing JCL will continue to execute correctly. • SMS allows the installation to benefit from the data class, management class, and storage class constructs without changing existing JCL. •The installation-written ACS routines can be designed to filter existing parameters on the DD statement and select appropriate constructs for the data set.
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Review Questions What are the different types of VSAM files? KSDS, ESDS, RRDS, LDS VSAM stores records in the data component in units called _______ Control intervals When we are using GDG’s then what do following versions mean in a JCL? (-1), (+0) & (+1). -1 – Version of data set previous to current existing +0 – Current existing version of data set +1 – New version of data set getting created
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Review Questions …. What is the limit on the maximum number of generations which can be kept for a GDG? 255
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Thank You! Copyright © 2005, Infosys 23 Technologies Ltd
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